🔍 Read the full analysis: Microsoft 365 Users Face Day Two Of Outage: What’s Happening on ThorstenMeyerAI.com
Get audio and creator gear delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
TL;DR
Microsoft 365 remained degraded as of 08:35 UTC on Nov. 13, after Exchange Online problems that began Thursday disrupted access to email and connected services. Microsoft reported improved stability on some servers after a patch and said it was expanding the fix by region; it has not identified the root cause.
Microsoft 365 was still experiencing service degradation at 08:35 UTC Friday, Nov. 13, after an outage that began the previous day disrupted Exchange Online email and services that depend on it. Microsoft said it had seen improved server stability after applying a patch to part of its infrastructure and was expanding the patch region by region, but the company had not disclosed the root cause.
Microsoft’s latest update, posted at 08:06 UTC under incident EX1550543, said servers were stable where the patch had been applied. The company said it had started expanding the change systematically, beginning with regions in or approaching peak business hours. The status page continued to list a service degradation, so the update did not mean the outage was resolved.
The incident affects users trying to reach Exchange Online mailboxes through Outlook on the web, desktop and mobile, as well as REST connections. Microsoft’s incident notices say the disruption may affect connectivity to other Microsoft 365 services, including Teams calendars and meeting scheduling, parts of SharePoint Online, Copilot, the Defender XDR portal, Purview and Planner.
Microsoft’s account of the problem developed over Thursday night and Friday morning. It first cited elevated load across regions, then said the load was not caused by increased traffic but by servers becoming unexpectedly unavailable. The company paused deployments, shifted traffic, restarted servers and changed its server-health checks. It later reported that a core process was becoming overwhelmed and that servers returning to service could become unresponsive again under traffic.
At 07:29 UTC Friday, Microsoft reported positive server-stability results after applying an upstream authentication and routing configuration component patch to part of its infrastructure. The 08:06 update said the patch expansion was underway. Microsoft has not said how many servers or regions were covered at that point, or when service would be fully restored.
Microsoft 365 outage · Nov 12–13, 2026 · times UTC
Down, rerouted, restarted, down again
How Microsoft described the outage, step by step, in its own status posts.
Server pool (schematic)
servingcarrying extra loadunavailablerestart
What Microsoft said
- 17:54Nov 12Mailbox access fails in the Americas
- 18:07“May affect” users “in any region”
- 18:35“Elevated load across multiple regions”
- 19:12All deployments paused, traffic moved, servers restarted
- 19:31Not more traffic: servers “unexpectedly unavailable”, the rest carry the load
- 21:00New health-check method: some servers back in service
- 23:59Returned servers “can become unresponsive again”
- 08:06Nov 13Patch stable where applied, now expanding region by region; still degraded
Hit
Exchange Online mail in Outlook, Teams calendars, SharePoint features, Microsoft 365 Copilot, Defender XDR portal, Purview and more
AI connectors
OpenAI and Anthropic reported errors in their Microsoft 365 connectors
Earnings call moved
Workhorse Group: from Nov 12 to Nov 16, citing the Microsoft outage
Sources: Microsoft 365 Status on X (Nov 12, 17:54–21:00 UTC); Microsoft service health EX1550543 (Nov 12, 23:59 UTC; Nov 13, 08:06 UTC) and status.cloud.microsoft MO1550821 (Nov 13, 07:29 UTC); Anthropic and OpenAI status pages; Workhorse Group press release, Nov 12, 2026. Server pool is a schematic, not real server counts.
Graphic: Powered by Thorsten Meyer AI
Email Disruption Spreads Across Microsoft 365
The outage matters beyond access to inboxes because several workplace tools rely on Exchange Online. A loss of mailbox access can also interfere with calendar use, meeting scheduling and connected workflows, leaving organizations with reduced access to systems they use for daily operations. The scope and severity may vary by user and region; Microsoft’s service notice describes potential effects, not a confirmed tally of every affected customer.
There have also been reported knock-on effects outside Microsoft’s own services. The source material says OpenAI and Anthropic reported errors in their Microsoft 365 connectors. Workhorse Group moved its third-quarter earnings call from Nov. 12 to Nov. 16 because of the outage, according to the company’s announcement as described in the source. These examples show how disruptions to a shared platform can affect other services and scheduled business activity.
Reports on outage-tracking sites indicate widespread complaints, but they are not a count of people who lost access. Reuters, in a report published by The Korea Times, said Downdetector recorded more than 130,000 U.S. reports of Outlook problems at the peak, around 1 p.m. ET Thursday. Business Standard, citing Downdetector, reported reports from 74 countries. Downdetector aggregates user submissions, so these figures describe reports, not verified affected users or the total scale of the outage.
Products Worth Considering
Logitech MX Master 4 Ergonomic Wireless Mouse with Haptic Feedback, Graphite
EcoFlow DELTA 3 Max Portable Power Station, 2048Wh LFP Battery
Apple Watch Series 11 GPS + Cellular, 46mm Jet Black Aluminum Case with Black Sport Band (M/L)
As an affiliate, we earn on qualifying purchases.
How Thursday’s Incident Developed
The first public notice came at 17:54 UTC Thursday, when the Microsoft 365 Status account on X said the company was investigating reports of Exchange Online mailbox access problems through multiple connection methods in the Americas. A copy of the service-health post on Cloud Admin Hub lists the incident start as 16:17 UTC. At 18:07 UTC, Microsoft said the issue might affect connectivity for users in any region.
Microsoft’s updates then described attempts to restore capacity. It redistributed traffic, paused deployments and restarted affected servers. At 20:19 UTC, the company said its investigation pointed to a component responsible for processing server health as a possible source of failed checks, while noting it had not identified a recent change correlated with the start of the impact. Later, it said a core process was becoming overwhelmed and causing capacity loss.
At 01:06 UTC Friday, Microsoft said a process involved in establishing secure connections was becoming overwhelmed and stopping servers from processing requests. It also said it had begun reverting a recent network configuration change that correlated with the start of the incident. By 02:54 UTC, the company reported that a change it had applied was not working as expected. A separate Teams incident earlier Thursday, tracked as TM1550488, was marked fully resolved at 17:09 UTC. Microsoft has not said whether it was related to EX1550543.
“Servers are stable where the patch was applied, and we have initiated its expansion systematically.”
— Microsoft, in its 08:06 UTC service-health update for EX1550543
Cause and Recovery Scope Remain Unknown
Microsoft has not named a root cause or explained why the affected servers and processes became unavailable or overwhelmed. The company said it had not identified a recent change correlated with the start of the impact, then reported that a network configuration change correlated with the incident and that it had begun reverting it. Those statements describe investigative findings and actions, not a confirmed explanation of the underlying failure.
It is also not clear how many customers, servers or regions remained affected at 08:35 UTC, how quickly the patch would reach the rest of the infrastructure, or when Microsoft would declare service restored. The outage figures cited from Downdetector are user reports rather than verified counts of affected people. Microsoft said it was not aware of malicious activity, but that statement does not provide a technical root-cause determination.
Microsoft Expands the Regional Patch
Microsoft said it would continue expanding the patch region by region, prioritizing regions in or entering peak business hours, and monitor server stability as traffic returns. Users and organizations should check Microsoft’s service-health page for updates to incident EX1550543; the 08:35 UTC status in the source material still showed degradation, with no restoration time provided.
Microsoft has promised a Post-Incident Report after the problem is mitigated. That report is expected to provide more detail about the cause and response, but the company had not published it at the time of the latest update. Until Microsoft reports full recovery, the timing and extent of further service interruptions remain uncertain.
Key Questions
Is the Microsoft 365 outage over?
No. As of 08:35 UTC on Nov. 13, Microsoft’s status page still listed a service degradation. The company reported improved stability on some patched servers but had not declared the incident resolved.
Which services are affected?
The incident centers on Exchange Online mailbox access through Outlook and REST connections. Microsoft said connectivity issues may also affect dependent services, including Teams calendars and meeting scheduling, parts of SharePoint Online, Copilot, Defender XDR, Purview and Planner.
What has Microsoft said caused the outage?
Microsoft has not confirmed a root cause. It has described unexpectedly unavailable servers, failed health checks and an overwhelmed process involved in establishing secure connections. It also said a network configuration change correlated with the start of the incident and that it had begun reverting it.
What is Microsoft doing to restore service?
Microsoft reported positive stability results after applying an authentication and routing configuration component patch to part of its infrastructure. It said it was expanding the patch systematically by region and monitoring the affected servers.
Do outage-tracker reports show how many people were affected?
No. Downdetector figures cited in reports count user-submitted problem reports, not verified affected users. They indicate the volume and geographic spread of complaints but do not establish how many people lost access.
Source: ThorstenMeyerAI.com
